The present invention relates to a nuclear power plant and more especially to a nuclear power plant having a closed gas-cooling circuit and a plurality of heat-utilizing circuits or loops.
The design according to the invention offers the advantage that only the resulting mechanical or electrical yield is actually removed from the concrete pressure tank, aside from the cooling water which does not come into contact with the contaminated gas. As a result, the external space surrounding the concrete pressure vessel is effectively protected against contaminated gases, while the internal space of the vessel is utilized optimally. The decisive advantage of the design under the invention is the fact that the high-temperature medium is not carried to merely one gas-turbine assembly of relatively large dimensions (as is the case with most conventional nuclear reactors equipped with a closed gas-cooling circuit,) but that a plurality of relatively small gas-turbine assemblies are installed inside the concrete vessel. The several smaller turbine assemblies are linked to the nuclear reactor, each constituting a separate thermodynamic circuit (loop) each with its own heat exchanger. Through an integrated design, i.e., by installing all components, such as the nuclear reactor, the gas turbine assemblies and the connecting tubing inside one common pressure vessel, the need for any special connectors between active gas containing components is eliminated. This fact is of decisive advantage in the construction and operation of high-temperature reactors.
German Offenlegungsschrift No. 1,764,249 discloses a nuclear power plant of the general type defined, in which the nuclear reactor and the heat exchanging components are installed in tightly spaced, parallel and vertical shafts surrounded by a pressure-tight vessel made of reinforced concrete, with all components accessible from the outside. A primary turbine stage driving an electric generator is installed in a horizontal shaft, while the compressor, together with a secondary turbine stage which drives it, are installed in one vertical shaft, one positioned vertically directly above the other. The recuperator, because of its magnitude, has been divided into two separate sections connected in series, and both sections are installed in one vertical pod. Passageways are provided in the wall of the concrete pressure vessel and in the concrete material between the pods to allow for the circulation of cooling media, such as CO.sub.2. In one preferred prototype, the nuclear power plant comprises three parallel thermodynamic circuits (loops), each loop comprising two turbine stages, one generator, one compressor, and various heat-exchanging components, with the loops being grouped symmetrically around the reactor core. Each of the three recuperators is likewise subdivided into two distinct sections. The cooling media thereby must traverse very great distances, necessitating a pressure vessel of relatively large dimensions.
The German Offenlegungsschrift No. 1,764,355 likewise describes a gas-cooled nuclear reactor of integrated design in which the circulatory components, installed in tandem inside a pressure-proof concrete vessel, have been coupled by tubular channels. The entire installation comprises two identical thermodynamic circuits (loops), each of which comprises, on a common shaft, a high- and a low- pressure compressor and a gas turbine, as well as several coolers and recuperators. The coolers and recuperators are installed in a circle around the reactor and are seated in honeycomb-like recesses in the vessel wall, and each cooler is installed vertically atop its respective recuperator in the same recess. The two turbines with their respective compressors are installed in a cavity underneath the reactor together with the distributive tubing system serving the recuperators and coolers. The turbines are installed parallel to one another.
Another nuclear power plant of basically similar design is described in German Auslegeschrift No. 1,806,471. In this disclosure, not only the system of heat exchangers has been placed in parallel vertical shafts inside the wall of the concrete pressure vessel, but also the turbine assemblies comprising the compressor turbine, the power turbine and other compression devices. In one embodiment of such a plant three turbines systems are connected to the reactor as a heat source. The turbines are installed symmetrically about and parallel to the reactor. Each thermodynamic circuit (loop), together with all its pertinent components, is installed in one vertical shaft surrounded by a housing.
Lastly, German Offenlegungsschrift No. 2,062,934 may be mentioned, which likewise describes a gas-cooled nuclear reactor equipped with multiple, coupled turbine assemblies which are coupled with the nuclear reactor and are installed in vertical shafts inside the wall of the pressure vessel. By means of a by-pass device, a part of the cold gas moving in the direction of the reactor core can be diverted and mixed directly with the heated cooling gas emerging from the reactor core.